Electrical measuring instrument



June '17, 1930. v c. OMAN I 1,764,339

ELECTRICAL MEASURING INSTRUMENT Filed Aug. '9, 1924 MATE/W141 HA V/WQ A TEMPE/FA TU/PE COEFF/ C/E/Yl' OF/FESl-S TA/I/CE OF 14 5007' T/I'AT OF COPPER LANE ' VOLTAGE.

T SERKES FLUX ZHUNTT' LU'X T 1 WITNESSES: 2 INVENTOR Z. A M I car/ 0070/? E i E I BY ATTORNEY 45- relation of mama June i7, 1930* UNITED STATES PATENT ormcr.

- I CARL m, 01' SWISSVALE, PENNSYLVANIA, ASSIGNOB T0 WESTINGHOUSE ELEG- TRIO & IANUFACTUBIN G COMPANY,

A CORPORATION OF PENNSYLVANIA.

amnion nnn'sunme msrauum Application nee August a, 1924. Serial in. 731,054.

My invention relates to electrical measuring instruments and particularly to induction meters.

One object of my invention is to provide 5 an instrument, of the above indicated character, in which the movable element shall rotate in substantially fixed relation to a circuit load, irrespective of temperature v a riations in the instrument. I

. Another objectof my invention is to provide a watthour meter that shall be so compensated for leadin and lagging power factors as to accurate y register the consumed energy under all conditions of operation.

In a watthour meter of the induction type, the flux from the series poles is in phase with the current in the series windings and, at unity power factor, the flux from the shunt pole is ninety degrees out of phase with the current in the shunt winding. Consequently, at unity power factor, where the current and voltage are in phase, the fluxes from the series and shunt poles are ninety degrees out of phase, producing a composite actuating flux in fixed relation to the circuit load and rotating the meter element in accordance with the energy or watthour-consumption.

As the power factor of the circuit leads or lags, the shunt current leads or lags the series current, resulting in a displacement between the series and shunt fluxes which causes the meter element to rotate faster or slower in accordance with the degree and direction of power factor change.

In an endeavor to have the meter operate accurately at all power factors, 'it has been usual to provide a closed circuit loop of copper or other material on the shunt pole.

' The resistance of the loop may be selected I 40 to cause the meter to operate accurately at all power factors under constant temperature conditions; However, changes in temperature cause the resistance of the loop to 'vary, thereb changing the phase-angular 0 series and shunt fluxes and causing a corresponding'error in the meter reading.

It is my aim to overcome the above mentioned ob ection and to provide a meter that shall operate in substantially fixed relation to its lp'ad under all temperature and powerfactor conditions. g

Accordingly, in practicing my invention, I provide a meter, the series and shunt fluxes of which are both compensated by closed circuit loops of such construction, relation and temperature coeificients' as to compensate for 0th power factor and temperature changes in a manner permitting the accurate operation of the meter at all times.

Figure 1 of the accompanying drawing is a perspective view of the field-magnet structure of a watthour meter, with its usual coils and the closed circuit loops of my invention represented diagrammatically, and

Figure 2 is a vector diagram showing a relation between the line current and voltage and the meter fluxes. i

The device comprises, in general, a laminated field-magnet structure 1' of usual con-.

s struction having a shunt pole portion 2 and a pairof series pole portions 3. A voltage coil 5' and current coils 6 are disposed on the pole portions 2 and 3, respectively, and are adapted for connection to a circuit in a usual and well-known manner. I

The usual copper or aluminum disk for operation in the air gap 7 between the pole portions 2 and 3, together with the meter shaft, registering mechanism and other standard arts have been omitted from the drawing fiir simplicity and clearness and be cause the construction and operation ofthese parts are so well-known to those versed in the art as to be deemed unnecessary of illustration in the drawing for a full and com plete understanding of the invention. A closed circuit conducting loop 9 embraces the shunt-pole portion 2 at a position adjacent to the air gap 7. It has been usual particular characteristics or for t e same purpose as the loop 9, as will hereinafter be set forth.

As hereinbefore explained, a loop in the place of the loop 9 has heretofore been provided to alone compensate for changing power factor. Such a loop has been sub ect to changes in resistance which caused errors in the meter operation, as described. However, in the present construction, the loop 9 co-operates with another closed c1rcu1t loop 10 on the series pole portions 3. The loop 10 is formed tothe shape of a figure eight, the ends of which surround the pole portions 3 in opposite directions in accordance with the direction of flux flow in these poles that is determined by the series coils 6 which are also wound oppositely around the pole portions 3.

The loop 9 is constructed of brass or other suitable material having a lower temperature coeflicient than the loop 10 which may be of copper or other material so that the resistances of the loops change at diflerent rates with changin temperature. With the resistance values oi the loops: 9 and 10 originally selected or adjusted to roperly compensate the meter for poweractor c anges and with the 'difierential temperature resistance change properly balanced, the actuatmg flux from the pole portions 2 and 3 will be maintained in substantially constant relation tothe load for all power-factor and temperature conditions within the range of the instrument.

This may be more clearly understood froma consideration of Fig. 2, in which the line current and voltage and the series and shunt fluxes are shown in their relation at unity power factor. At thispower factor, the line current and voltage are in phase.

- ance of the shunt loop 9 and the shunt coil 5.

The phase-angle error, referred to as occurring in the prior art meters, would here be introduced, if the series flux did not also assume a new position, as indicated.

However, by reason of a change in the resistance of the copper loop 10 on the'series poles, the series flux assumes the new position and thus maintains the angle between the fluxes at a constant value of ninety degrees.

At any other power factor, the angle between the series and shuntfluxes'is (90a:)

degrees, where a: is the angle that the current lags or leads the voltage, a: being positive for lagging current and negative for leadin current.

bus, as above explained for unity power factor conditions, the value of the angle (90-00) degrees will be retained independent of temperature changes.

While I have shown and described a particular form of my invention, changes may be efiectedtherein without departing from the spirit and scope thereof, as set forth in the appended claims.

I claim as my invention:

1. The combination with an electro-responsive device comprising voltage and current means for creating a plurality of co-operating fluxes therefor, of means responsive to temperature changes for inductively affecting ing persistence of substantially the same phase angle between the voltage and current producing said fluxes.

3. In an induction meter, the combination with means for creating angularly displaced actuating fluxes, of stationaryv means for simultaneously inductively aflecting each of said fluxes in response to temperature changes to maintain said fluxes in substantially constant phase relation during persistence of substantially the same phase angle between the voltage and current producing said fluxes.

4:. In an induction meter, the combination with a field-magnet structure having a plurality of pole portions and means for energizing the pole portions to provide angulary displaced actuating fluxes for the meter, of stationary means on said pole port-ions responsiveto temperature changes for inductively affecting each of said fluxes and maintaining the same in substantially constant phase relations during persistence of substant tially the same phase angle be ween the VOILE age and current producing said fluxes.

5. In an induction meter, the combination with a field-magnet structure having a plurality of pole portions and means for energizing the pole portions to provide angularly displaced actuating fluxes for the meter, 01 differentially acting closed-circuit'loops on said pole' portions responsive to temperature changes for aflecting each of said fluxes and maintaining the same in substantially constant phase relation for a given power factor with a field-magnet core member having a shunt pole portion and a pair of series pole portions, of a closed-circuit loop of predetermined temperature coeflicient extending around the series pole portions, and a closedcircuit loop of different temperature coeflicient su'rounding the shunt pole portion.

7. In an induction meter, the combination with a field-magnet core member having a shunt pole portion and a pairoi series pole portions, of a closed circuitloop of predetermined temperature coeflicient extending around the series pole portions in reverse directions, and a closed-circuit loop of lower temperature coefiicient surrounding the shunt pole portion.

8. The combination with an electro-responsive device comprising means for creating a plurality of co-operating alternating fluxes therefor, of stationary means responsive to temperature changes for inductively afiecting eachof said fluxes and maintaining the same in substantially constant phase relation during persistence of substantially thesame phase angle between the current and voltage producing said fluxes. w 9. The combination with a magnetizable structure in which alternating fluxes are pro-' duced, respectively, by the current and voltage of an electrical circuit, of stationary means responsive to temperature changes for inductively aflecting and maintaining said fluxes in substantially constant phase relation during persistence of substantially the same phase angle between the current and voltage.

10. In an induction meter, the combination with a magnetizable structure comprising shunt aiid series pole portions, and closed loops off conducting material inductively related, respectively, to said shunt and saidv series pole portions, said closed loops of conducting material having different temperature coefiicients of resistance. v

11. The combination with a magnetizable structure having portions in which fluxes are produced, respectively, by the current and the voltage of an electrical circuit, of means for maintaining said fluxes in substantially constant phase relation when subjected .to temperature changes during persistence of substantially the same phase angle between-said current and said voltage comprising closed-' circuit loops of materials having diflerent temperature coefiicients of resistance inductively related, respectively, to the portions of said magnetizable structure in which said current and'said potential fluxes are produced.

12. The combination with a core and current and voltage means for producing a plurality of coactin alternating fluxes in said core, of means or maintain-'- magnetizable ing said fluxes in substantially unchanging phase relationship upon changes in temperatureand during persistence of substantially the same phase angle between the current and voltage producing said fluxes comprising sep-' arate coils of diiferent temperature coeflicients of resistance coacting with said flux producing means.

13. The combination with a current winding anda voltage winding for producing a plurality of coacting alternating fluxes, of means for maintaining the phase angle between said fluxessubstantially fixed, during. persistence of substantially the same phase angle between the current and voltage producing said fluxes, regardless of temperature changes, comprising induction means having difierent temperature coeflicients of resistance associated with said current and voltage windings.

14. In an electricity meter, the combination with a movable element, of shunt and series torque producing circuits therefor, variations in temperature tending to cause variations in the phase relationship between the fluxes of said shunt and series torque-producing circuits and stationary means associated with said torque-producing circuits for influencing the fiuxesthereof whereby tendencies to variations in the phase relationship between the said shunt and series torque-producing circuits, and stationary means responsive to tem erature variations inductively related to said t rque-producing. circuits for influencing the fluxes thereof whereby tendencies to variations in the phase relationship between the fluxes of said shunt and series circuits, under constant load condition of said series circuit,

will be substantially obviated.

16. An electric meter of the'induction type comprising a rotor, a magnetizable member having potential and series windings thereon, temperature-error compensating -means cooperating with said potential winding, and

means associated with said series winding and coacting with said temperature-error compensating means for maintaining substantially fixed the phase angular relationship between the fluxes of said potential and series windings during persistence of substantiaily thesame phase angle between the current and voltage producing said fluxes,

regardless of temperature changes,

x 17. An electric meter of the induction type comprising; a rotor, a magnetizable member having potential and series windings-thereon, a lag loop for said potential winding and a lag loop for said series winding, said leg loops having cients of resistance for maintainin dissimilar temperature coeflisubstantially fixed the phase angular re ationship between the fluxes of said potential and series windings, during persistence of substantially the same phase angle of the current and voltage producing said fluxes, regardless of temperature changes.

3 In testomony whereof, I have hereunto subscribed my name this 2nd day of August,

CARL OMAN. 

